The present disclosure lies in the field of dosing units for an ambulatory infusion system. The disclosure lies further in the field of drive units for use in combination with a dosing unit as well as in the field of ambulatory infusion systems for infusing a liquid drug into a patient's body over an extended time period. Furthermore, the disclosure lies in the field of methods for coupling a dosing unit and a drive unit.
Ambulatory infusion devices are well known in the art for example in the therapy of diabetes mellitus by continuous subcutaneous insulin infusion (CSII) as well as in pain therapy or cancer therapy and are available from a number of supplies, such as Roche Diagnostics GmbH, Germany, or Medtronic MiniMed Inc., CA, USA.
According to a classic and well-established design, those ambulatory infusion devices or systems are typically of the syringe-driver type. A number of drawbacks of such devices are known in the art. In particular, they have a limited precision because they involve delivering very small drug amounts, typically in the nanoliter range, out of a drug cartridge having an overall drug volume in the millilitre range. Therefore, additional concepts and architectures have been proposed which use a dedicated dosing unit downstream from the drug reservoir, comprising, e.g., a micro membrane pump or a micro piston pump and are adapted to couple to a drug reservoir and especially designed for precise metering of small volumes. While several designs for such dosing units are known in the art, they are rather complex, most of them are expensive and/or critical with respect to large scale manufacture.
The EP1970677A1 discloses a system with a miniaturized metering piston pump with a dosing cylinder that is repeatedly coupled to and filled from a larger reservoir, followed by coupling the dosing cylinder to an infusion site and infusing the liquid drug out of the dosing cylinder in incremental steps and over an extended time period. For alternatively coupling the dosing cylinder to the reservoir and the infusion site, a valve system is proposed.